This invention relates to dynamoelectric machines generally, and, more specifically, to a new tapered slide component in a stator slot wedging system used to secure an armature winding in medium and large generators.
Stator winding wedge systems are designed to maintain radial pressure on the armature bars and slot components of a generator to thereby prevent the damaging effects of electromagnetic vibration forces. As the generator operates, load induced compressive creep and slot component material shrinkage cause a reduction in the radial force, which eventually results in a detectable loose wedge condition. Currently, when the wedging system of a generator becomes loose after operation for some time, the generator must be re-wedged. The present re-wedging process involves rotor removal and also removal of all of the old wedging material and subsequent replacement with new components.
This problem has been addressed previously in prior U.S. patent documents. For example, commonly owned U.S. Pat. No. 6,331,745 describes an adjustable slide that provides for an interlocking surface between the wedge and slide. The mating surfaces of the wedge and slide have a saw tooth pattern to allow for interlocking of the pieces to prevent reverse axial movement of the slide. The material and machining of the saw tooth pattern is very expensive and it is prohibitive to use this design throughout the entire length of the stator and, in fact, it is only adaptable to wedges located at the ends of the stator slot.
U.S. Pat. No. 4,149,101 describes another arrangement for locking the slot wedges, but it is also applied only to the end portion of the slot only.
U.S. Pat. No. 5,598,049 describes a slot sealing arrangement in which the elasticity of the wedge and slide are utilized to obtain optimum radial force along the entire central length of the wedge. No capability for preventing reverse axial movement of the slide is disclosed.